DSpace Collection:http://hdl.handle.net/2381/2692018-02-18T05:07:46Z2018-02-18T05:07:46ZRethinking public ownership: Experimenting with InstitutionsLast, Angelahttp://hdl.handle.net/2381/411592018-02-15T03:23:52Z2018-02-14T09:33:02ZTitle: Rethinking public ownership: Experimenting with Institutions
Authors: Last, Angela
Abstract: The word ‘institution’ tends to attract at best a conditional appreciation and at worst a complete aversion. The aversion is usually triggered by some form of exposure to institutional violence through bureaucracy or enforcement of undesirable norms; while a conditional appreciation usually stems from a general welcoming of [End Page 99] institutional safety nets combined with an awareness of their potentially oppressive downsides. In their Kilburn Manifesto contribution ‘States of Imagination’, Janet Newman and John Clarke describe a similar relationship between people and the state: the state is both loathed and desired under current political conditions, since it has the capacity to function both as a tool of neoliberal policies and as a ‘bulwark’ against them.1 As more and more institutions of the welfare state, including the National Health Service, are being dismantled, the question of what kinds of institutions we actually want has become more urgent. Do we want to protect the institutions we already have, which we need but feel ambiguous about, or are there better alternatives?2018-02-14T09:33:02ZTo Risk the Earth: the Nonhuman and NonhistoryLast, Angelahttp://hdl.handle.net/2381/411582018-02-14T03:29:38Z2018-02-13T15:11:03ZTitle: To Risk the Earth: the Nonhuman and Nonhistory
Authors: Last, Angela
Description: The file associated with this record is under embargo until 12 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.2018-02-13T15:11:03ZFrontiers Review: Experimental analysis of soft-tissue fossilization – opening the black boxPurnell, Mark A.Donoghue, Philip J. C.Gabbott, Sarah E.McNamara, MariaMurdock, Duncan J. E.Sansom, Robert S.http://hdl.handle.net/2381/411272018-02-09T03:24:03Z2018-02-08T11:33:28ZTitle: Frontiers Review: Experimental analysis of soft-tissue fossilization – opening the black box
Authors: Purnell, Mark A.; Donoghue, Philip J. C.; Gabbott, Sarah E.; McNamara, Maria; Murdock, Duncan J. E.; Sansom, Robert S.
Abstract: Taphonomic experiments provide important insights into fossils that preserve the remains of
decay-prone soft tissues – tissues that are usually degraded and lost prior to fossilization. These
fossils are among the most scientifically valuable evidence of ancient life on Earth, giving us a view
into the past that is much less biased and incomplete than the picture provided by skeletal remains
alone. Although the value of taphonomic experiments is beyond doubt, a lack of clarity regarding
their purpose and limitations, and ambiguity in the use of terminology, are hampering progress.
Here we distinguish between processes that promote information retention and those that promote
information loss in order to clarify the distinction between fossilization and preservation.
Recognising distinct processes of decay, mineralization and maturation, the sequence in which
they act, and the potential for interactions, has important consequences for analysis of fossils, and
for the design of taphonomic experiments. The purpose of well-designed taphonomic experiments
is generally to understand decay, maturation, and preservation individually, thus limiting the
number of variables involved. Much work remains to be done, but these methodologically
reductionist foundations will allow researchers to build towards more complex taphonomic
experiments and a more holistic understanding and analysis of the interactions between decay,
maturation and preservation in the fossilization of non-biomineralized remains. Our focus must
remain on the key issue of understanding what exceptionally preserved fossils reveal about the
history of biodiversity and evolution, rather than on debating the scope and value of an
experimental approach.
Description: The file associated with this record is under embargo until 12 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.2018-02-08T11:33:28ZComparative approaches to gentrification: lessons from the ruralSmith, Darren P.Phillips, Martinhttp://hdl.handle.net/2381/411112018-02-08T03:24:47Z2018-02-07T14:47:48ZTitle: Comparative approaches to gentrification: lessons from the rural
Authors: Smith, Darren P.; Phillips, Martin
Abstract: x
Description: The file associated with this record is under embargo until publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.2018-02-07T14:47:48ZResisting Planetary Gentrification: The Value of Survivability in the Fight to Stay PutLees, LorettaAnnunziata, SandraRivas-Alonso, Clarahttp://hdl.handle.net/2381/411072018-02-08T03:24:47Z2018-02-07T13:43:00ZTitle: Resisting Planetary Gentrification: The Value of Survivability in the Fight to Stay Put
Authors: Lees, Loretta; Annunziata, Sandra; Rivas-Alonso, Clara
Abstract: In-depth studies of and attempts to theorize or conceptualize resistance to gentrification have been somewhat sidelined by attention to the causes and effects of gentrification in the now rather extensive gentrification studies literature. Yet resistance to gentrification is growing internationally and remains a (if not the) key struggle with respect to social justice in cities worldwide. In this article, we address this gap head on by (re)asserting the value of survivability for looking at resistance to gentrifications around the globe. U.S. urban scholars have been at the forefront of writing about resistance to gentrification, especially in cities like San Francisco and New York City, but in a situation of planetary gentrification it is imperative that we learn from other examples. Critically, we argue that practices of survivability can be scaled up, down, and in between, enabling the building of further possibilities in the fight against gentrification, the fight to stay put. There needs to be a stronger and more determined international conversation on the potential of antigentrification practices worldwide and here we argue that survivability has a lot to offer these conversations.2018-02-07T13:43:00ZExplosive eruptive history of Pantelleria, Italy: Repeated caldera collapse and ignimbrite emplacement at a peralkaline volcanoJordan, Nina J.Rotolo, Silvio G.Williams, RebeccaSperanza, FabioMcIntosh, William C.Branney, Michael J.Scaillet, Stéphanehttp://hdl.handle.net/2381/410032018-01-25T03:30:01Z2018-01-24T14:58:23ZTitle: Explosive eruptive history of Pantelleria, Italy: Repeated caldera collapse and ignimbrite emplacement at a peralkaline volcano
Authors: Jordan, Nina J.; Rotolo, Silvio G.; Williams, Rebecca; Speranza, Fabio; McIntosh, William C.; Branney, Michael J.; Scaillet, Stéphane
Abstract: A new, pre-Green Tuff (46 ka) volcanic stratigraphy is presented for the peralkaline Pantelleria Volcano, Italy. New 40Ar/39Ar and paleomagnetic data are combined with detailed field studies to develop a comprehensive stratigraphic reconstruction of the island. We find that the pre-46 ka succession is characterised by eight silica-rich peralkaline (trachyte to pantellerite) ignimbrites, many of which blanketed the entire island. The ignimbrites are typically welded to rheomorphic, and are commonly associated with lithic breccias and/or pumice deposits. They record sustained radial pyroclastic density currents fed by low pyroclastic fountains. The onset of ignimbrite emplacement is typically preceded (more rarely followed) by pumice fallout with limited dispersal, and some eruptions lack any associated pumice fall deposit, suggesting the absence of tall eruption columns. Particular attention is given to the correlation of well-developed lithic breccias in the ignimbrites, interpreted as probable tracers of caldera collapses. They record as many as five caldera collapse events, in contrast to the two events reported to date. Inter-ignimbrite periods are characterised by explosive and effusive eruptions with limited dispersal, such as small pumice cones, as well as pedogenesis. These periods have similar characteristics as the current post-Green Tuff activity on the island, and, while not imminent, it is reasonable to postulate the occurrence of another ignimbrite-forming eruption sometime in the future.
Description: The file associated with this record is under embargo until 24 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.2018-01-24T14:58:23ZInvestigation of organic matter and biomarkers from Diepkloof Rock Shelter, South Africa: insights into Middle Stone Age site usage and palaeoclimateCollins, James A.Carr, Andrew S.Schefuss, EnnoBoom, ArnoudSealy, Judithhttp://hdl.handle.net/2381/409922018-01-25T03:30:19Z2018-01-24T13:23:50ZTitle: Investigation of organic matter and biomarkers from Diepkloof Rock Shelter, South Africa: insights into Middle Stone Age site usage and palaeoclimate
Authors: Collins, James A.; Carr, Andrew S.; Schefuss, Enno; Boom, Arnoud; Sealy, Judith
Abstract: Diepkloof Rock Shelter (DRS) represents a site of major interest for reconstructing early human behaviours during the Middle Stone Age (MSA). Rock shelters such as DRS also potentially preserve information concerning the environmental context for such behaviours. In this respect the organic matter composition of rock shelter sediments has rarely been investigated in detail, particularly at the molecular level. Here, we used pyrolysis-gas chromatography/mass spectrometry (py-GC/MS) to systematically assess the organic matter composition of bulk sediments within the MSA and Later Stone Age (LSA) sequence at DRS. From this we sought to gain insights into site usage, taphonomy and burning practices. Additionally, we analysed the chain length distribution of leaf-wax n-alkanes as well as their hydrogen and carbon isotopic compositions (δDwax and δ13Cwax) to investigate their potential as hydroclimate and vegetation indicators. This constitutes the first leaf-wax isotopic data in a terrestrial context of this antiquity in South Africa.
Py-GC/MS shows a dichotomy between stratigraphic units (SUs) of high organic matter content, producing a range of pyrolysis products, including homologous series of long chain n-alkene/n-alkane doublets and alkyl-nitriles, and SUs of low organic matter content, dominated by aromatic, heterocyclic N and polycyclic aromatic hydrocarbon (PAH) pyrolysis products; typical molecular burning products. Several SUs of the Intermediate Howiesons Poort interval exhibit the latter composition, consistent with micromorphological evidence.
δ13Cwax remains stable throughout the MSA, but leaf-wax n-alkane chain length and δDwax increase during the Late Howiesons Poort interval. Comparison with such patterns in modern plants in the region suggests this represents a shift towards the input of more arid-adapted vegetation into the shelter, driven either by aridification at the site locale or a change in selection practices. Our results suggest that these techniques have further potential in southern Africa and globally at sites where organic matter preservation is high.
Description: The file associated with this record is under embargo until 36 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.2018-01-24T13:23:50ZStratification and sample allocation for reference burned area dataPadilla, MarcOlofsson, PontusStehman, Stephen V.Tansey, KevinChuvieco, Emiliohttp://hdl.handle.net/2381/409902018-01-25T03:30:29Z2018-01-24T12:16:20ZTitle: Stratification and sample allocation for reference burned area data
Authors: Padilla, Marc; Olofsson, Pontus; Stehman, Stephen V.; Tansey, Kevin; Chuvieco, Emilio
Abstract: Statistical estimation protocols are one of the key means to ensure that independent and objective information
on product accuracy is communicated to end-users. Methods for validating burned area products have been developed
based on a probability sample of a space by time partitioning of the population. We extend this basic
methodology to improve stratification and sample allocation, key elements of a sampling design used to collect
burned area reference data. We developed and evaluated an approach to partition each year and biome into low
and high burned area (BA) strata. Because the threshold used to separate the sampling units into low and high BA
can vary by year and biome, this approach offers a more targeted stratification than used in previous studies for
which a common threshold was applied to all biomes. A hypothetical population of validation data was then used
to quantitatively compare the precision of accuracy estimates derived from different stratification and sample
size allocation options. We evaluated two options that had been previously examined in the BA validation literature,
and extended previous studies by adding two new options specifically developed for ratio estimates. Stratification
based on mapped BA reduced standard errors of the global burned area accuracy estimates from one-half
to one-eighth relative to standard errors of simple random sampling. Stratifying by mapped BA was also found to
reduce standard errors of accuracy estimates for most year by biome strata indicating that this advantage of stratification
and sample allocation applies generally to a range of conditions (i.e., biomes and years). The most precise
estimates were obtained using a sample size per stratum allocation nh∝Nh SQRT(BAR(BAh)) where Nh is the number of units
in stratum h and BAR(BAh) is the mean mapped BA for stratum h. The best sampling design from our analyses was then
used to select a set of 1,000 samples from a hypothetical population of validation data and confidence intervals
were computed for each sample. Close to 95% of these confidence intervals contained the true population
value thus confirming the validity of confidence intervals produced from the estimates and standard errors2018-01-24T12:16:20ZCalogero Giametta, The Sexual Politics of Asylum: Sexual Orientation and Gender Identity in the UK Asylum System,Brown, Gavinhttp://hdl.handle.net/2381/409702018-02-06T11:55:16Z2018-01-23T12:02:29ZTitle: Calogero Giametta, The Sexual Politics of Asylum: Sexual Orientation and Gender Identity in the UK Asylum System,
Authors: Brown, Gavin
Abstract: Review of: Calogero Giametta, The Sexual Politics of Asylum: Sexual Orientation and Gender Identity
in the UK Asylum System, Abingdon: Routledge, 2017. ISBN: 9781138674677 (cloth); ISBN:
9781315561189 (ebook)
Description: The file associated with this record is under embargo until 24 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.2018-01-23T12:02:29ZClimatic controls on Later Stone Age human adaptation in Africa's southern CapeChase, Brian M.Faith, J. TylerMackay, AlexChevalier, ManuelCarr, Andrew S.Boom, ArnoudLim, SophakReimer, Paula J.http://hdl.handle.net/2381/409362018-01-18T03:25:34Z2018-01-17T14:07:31ZTitle: Climatic controls on Later Stone Age human adaptation in Africa's southern Cape
Authors: Chase, Brian M.; Faith, J. Tyler; Mackay, Alex; Chevalier, Manuel; Carr, Andrew S.; Boom, Arnoud; Lim, Sophak; Reimer, Paula J.
Abstract: Africa's southern Cape is a key region for the evolution of our species, with early symbolic systems, marine faunal exploitation, and episodic production of microlithic stone tools taken as evidence for the appearance of distinctively complex human behavior. However, the temporally discontinuous nature of this evidence precludes ready assumptions of intrinsic adaptive benefit, and has encouraged diverse explanations for the occurrence of these behaviors, in terms of regional demographic, social and ecological conditions. Here, we present a new high-resolution multi-proxy record of environmental change that indicates that faunal exploitation patterns and lithic technologies track climatic variation across the last 22,300 years in the southern Cape. Conditions during the Last Glacial Maximum and deglaciation were humid, and zooarchaeological data indicate high foraging returns. By contrast, the Holocene is characterized by much drier conditions and a degraded resource base. Critically, we demonstrate that systems for technological delivery – or provisioning – were responsive to changing humidity and environmental productivity. However, in contrast to prevailing models, bladelet-rich microlithic technologies were deployed under conditions of high foraging returns and abandoned in response to increased aridity and less productive subsistence environments. This suggests that posited links between microlithic technologies and subsistence risk are not universal, and the behavioral sophistication of human populations is reflected in their adaptive flexibility rather than in the use of specific technological systems.
Description: The file associated with this record is under embargo until 12 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.2018-01-17T14:07:31ZStratification and sample allocation for reference burned area dataPadilla, MarcOlofsson, PontusStehman, Stephen V.Tansey, KevinChuvieco, Emiliohttp://hdl.handle.net/2381/408852018-01-16T03:31:07Z2018-01-15T17:52:27ZTitle: Stratification and sample allocation for reference burned area data
Authors: Padilla, Marc; Olofsson, Pontus; Stehman, Stephen V.; Tansey, Kevin; Chuvieco, Emilio
Abstract: Statistical estimation protocols are one of the key means to ensure that independent and objective information on product accuracy is communicated to end-users. Methods for validating burned area products have been developed based on a probability sample of a space by time partitioning of the population. We extend this basic methodology to improve stratification and sample allocation, key elements of a sampling design used to collect burned area reference data. We developed and evaluated an approach to partition each year and biome into low and high burned area (BA) strata. Because the threshold used to separate the sampling units into low and high BA can vary by year and biome, this approach offers a more targeted stratification than used in previous studies for which a common threshold was applied to all biomes. A hypothetical population of validation data was then used to quantitatively compare the precision of accuracy estimates derived from different stratification and sample size allocation options. We evaluated two options that had been previously examined in the BA validation literature, and extended previous studies by adding two new options specifically developed for ratio estimates. Stratification based on mapped BA reduced standard errors of the global burned area accuracy estimates from one-half to one-eighth relative to standard errors of simple random sampling. Stratifying by mapped BA was also found to reduce standard errors of accuracy estimates for most year by biome strata indicating that this advantage of stratification and sample allocation applies generally to a range of conditions (i.e., biomes and years). The most precise estimates were obtained using a sample size per stratum allocation n[subscript h] ∝N[subscript h] x SQRT(BAR(BA[subscript h])) where N[subscript h] is the number of units in stratum h and BAR(BA[subscript h]) is the mean mapped BA for stratum h. The best sampling design from our analyses was then used to select a set of 1,000 samples from a hypothetical population of validation data and confidence intervals were computed for each sample. Close to 95% of these confidence intervals contained the true population value thus confirming the validity of confidence intervals produced from the estimates and standard errors.2018-01-15T17:52:27ZCorrection: Predictive Models of Primary Tropical Forest Structure from Geomorphometric Variables Based on SRTM in the Tapajós Region, Brazilian AmazonThe PLOS ONE Staffhttp://hdl.handle.net/2381/408332018-01-12T03:25:02Z2018-01-11T10:58:37ZTitle: Correction: Predictive Models of Primary Tropical Forest Structure from Geomorphometric Variables Based on SRTM in the Tapajós Region, Brazilian Amazon
Authors: The PLOS ONE Staff
Abstract: The article’s citation appears incorrectly in the published article. The correct citation is: Bispo PC, Santos JR, Valeriano MM, Graça PMLA, Balzter H, França H, et al. (2016) Predictive Models of Primary Tropical Forest Structure from Geomorphometric Variables Based on SRTM in the Tapajós Region, Brazilian Amazon. PLoS ONE 11(4): e0152009. doi:10.1371/journal.pone.0152009.
Description: Corrects http://hdl.handle.net/2381/375332018-01-11T10:58:37ZModelling forest canopy height by integrating airborne LiDAR samples with satellite Radar and multispectral imageryGarcia Alonso, MarianoSaatchi, SassanUstin, SusanBalzter, Heikohttp://hdl.handle.net/2381/408302018-01-12T03:25:03Z2018-01-11T10:39:21ZTitle: Modelling forest canopy height by integrating airborne LiDAR samples with satellite Radar and multispectral imagery
Authors: Garcia Alonso, Mariano; Saatchi, Sassan; Ustin, Susan; Balzter, Heiko
Abstract: Spatially-explicit information on forest structure is paramount to estimating aboveground carbon stocks for designing sustainable forest management strategies and mitigating greenhouse gas emissions from deforestation and forest degradation. LiDAR measurements provide samples of forest structure that must be integrated with satellite imagery to predict and to map landscape scale variations of forest structure. Here we evaluate the capability of existing satellite synthetic aperture radar (SAR) with multispectral data to estimate forest canopy height over five study sites across two biomes in North America, namely temperate broadleaf and mixed forests and temperate coniferous forests. Pixel size affected the modelling results, with an improvement in model performance as pixel resolution coarsened from 25 m to 100 m. Likewise, the sample size was an important factor in the uncertainty of height prediction using the Support Vector Machine modelling approach. Larger sample size yielded better results but the improvement stabilised when the sample size reached approximately 10% of the study area. We also evaluated the impact of surface moisture (soil and vegetation moisture) on the modelling approach. Whereas the impact of surface moisture had a moderate effect on the proportion of the variance explained by the model (up to 14%), its impact was more evident in the bias of the models with bias reaching values up to 4 m. Averaging the incidence angle corrected radar backscatter coefficient (γ°) reduced the impact of surface moisture on the models and improved their performance at all study sites, with R2 ranging between 0.61 and 0.82, RMSE between 2.02 and 5.64 and bias between 0.02 and −0.06, respectively, at 100 m spatial resolution. An evaluation of the relative importance of the variables in the model performance showed that for the study sites located within the temperate broadleaf and mixed forests biome ALOS-PALSAR HV polarised backscatter was the most important variable, with Landsat Tasselled Cap Transformation components barely contributing to the models for two of the study sites whereas it had a significant contribution at the third one. Over the temperate conifer forests, Landsat Tasselled Cap variables contributed more than the ALOS-PALSAR HV band to predict the landscape height variability. In all cases, incorporation of multispectral data improved the retrieval of forest canopy height and reduced the estimation uncertainty for tall forests. Finally, we concluded that models trained at one study site had higher uncertainty when applied to other sites, but a model developed from multiple sites performed equally to site-specific models to predict forest canopy height. This result suggest that a biome level model developed from several study sites can be used as a reliable estimator of biome-level forest structure from existing satellite imagery.
Description: Supplementary data associated with this article can be found, in the online version, at https://doi.org/10.1016/j.jag.2017.11.017.2018-01-11T10:39:21ZTooth microwear texture in odontocete whales: variation with tooth characteristics and implications for dietary analysisPurnell, Mark A.Goodall, Robert H.Thomson, ScottMatthews, Cory J. D.http://hdl.handle.net/2381/408282018-01-12T03:24:59Z2018-01-11T10:02:03ZTitle: Tooth microwear texture in odontocete whales: variation with tooth characteristics and implications for dietary analysis
Authors: Purnell, Mark A.; Goodall, Robert H.; Thomson, Scott; Matthews, Cory J. D.
Abstract: Understanding the diets and trophic relationships of toothed whales is central to understanding their roles in marine ecosystems, and associated conservation issues. Yet this is problematic because direct observation of what free ranging marine mammals eat is difficult. Quantitative 3D textural analysis of tooth microwear (DMTA) offers a new way of investigating diet in odontocetes and other marine mammals, but the application of this approach requires that we first understand how non-dietary variables affect the texture of microwear in odontocetes. Here we present the first analysis of microwear texture in odontocetes (beluga, Delphinapterus leucas) testing null hypotheses that microwear texture does not vary with dental surface tissue type (dentine, cementum), and that microwear texture does not vary with tooth characteristics (location in jaw, degree of wear, wear facet slope and facet orientation). Our results reveal that these variables have a significant impact on microwear textures, and thus have the potential to mask variation in texture caused by dietary differences. This does not mean that microwear texture analysis cannot be used as a tool for dietary analysis in toothed whales, but any future studies should adopt sampling protocols that standardize non-dietary variables to mitigate their effects in DMTA analysis.
Description: Supplementary data associated with this article can be found in the online version at http://dx.doi.org/10.1016/j.bsbt.2017.11.004.2018-01-11T10:02:03ZImpact of data model and point density on aboveground forest biomass estimation from airborne LiDAR.Garcia, MarianoSaatchi, SassanFerraz, AntonioSilva, Carlos AlbertoUstin, SusanKoltunov, AlexanderBalzter, Heikohttp://hdl.handle.net/2381/407852018-01-10T03:24:12Z2018-01-09T15:25:16ZTitle: Impact of data model and point density on aboveground forest biomass estimation from airborne LiDAR.
Authors: Garcia, Mariano; Saatchi, Sassan; Ferraz, Antonio; Silva, Carlos Alberto; Ustin, Susan; Koltunov, Alexander; Balzter, Heiko
Abstract: BACKGROUND: Accurate estimation of aboveground forest biomass (AGB) and its dynamics is of paramount importance in understanding the role of forest in the carbon cycle and the effective implementation of climate change mitigation policies. LiDAR is currently the most accurate technology for AGB estimation. LiDAR metrics can be derived from the 3D point cloud (echo-based) or from the canopy height model (CHM). Different sensors and survey configurations can affect the metrics derived from the LiDAR data. We evaluate the ability of the metrics derived from the echo-based and CHM data models to estimate AGB in three different biomes, as well as the impact of point density on the metrics derived from them. RESULTS: Our results show that differences among metrics derived at different point densities were significantly different from zero, with a larger impact on CHM-based than echo-based metrics, particularly when the point density was reduced to 1 point m-2. Both data models-echo-based and CHM-performed similarly well in estimating AGB at the three study sites. For the temperate forest in the Sierra Nevada Mountains, California, USA, R2 ranged from 0.79 to 0.8 and RMSE (relRMSE) from 69.69 (35.59%) to 70.71 (36.12%) Mg ha-1 for the echo-based model and from 0.76 to 0.78 and 73.84 (37.72%) to 128.20 (65.49%) Mg ha-1 for the CHM-based model. For the moist tropical forest on Barro Colorado Island, Panama, the models gave R2 ranging between 0.70 and 0.71 and RMSE between 30.08 (12.36%) and 30.32 (12.46) Mg ha-1 [between 0.69-0.70 and 30.42 (12.50%) and 61.30 (25.19%) Mg ha-1] for the echo-based [CHM-based] models. Finally, for the Atlantic forest in the Sierra do Mar, Brazil, R2 was between 0.58-0.69 and RMSE between 37.73 (8.67%) and 39.77 (9.14%) Mg ha-1 for the echo-based model, whereas for the CHM R2 was between 0.37-0.45 and RMSE between 45.43 (10.44%) and 67.23 (15.45%) Mg ha-1. CONCLUSIONS: Metrics derived from the CHM show a higher dependence on point density than metrics derived from the echo-based data model. Despite the median of the differences between metrics derived at different point densities differing significantly from zero, the mean change was close to zero and smaller than the standard deviation except for very low point densities (1 point m-2). The application of calibrated models to estimate AGB on metrics derived from thinned datasets resulted in less than 5% error when metrics were derived from the echo-based model. For CHM-based metrics, the same level of error was obtained for point densities higher than 5 points m-2. The fact that reducing point density does not introduce significant errors in AGB estimates is important for biomass monitoring and for an effective implementation of climate change mitigation policies such as REDD + due to its implications for the costs of data acquisition. Both data models showed similar capability to estimate AGB when point density was greater than or equal to 5 point m-2.
Description: The datasets supporting the conclusions of this article are available from the
authors upon request.2018-01-09T15:25:16ZRelationships of S-Band Radar Backscatter and Forest Aboveground Biomass in Different Forest TypesNingthoujam, Ramesh K.Balzter, HeikoTansey, KevinFeldpausch, Ted R.Mitchard, Edward T. A.Wani, Akhlaq A.Joshi, Pawan K.http://hdl.handle.net/2381/407842018-01-10T03:24:50Z2018-01-09T15:18:47ZTitle: Relationships of S-Band Radar Backscatter and Forest Aboveground Biomass in Different Forest Types
Authors: Ningthoujam, Ramesh K.; Balzter, Heiko; Tansey, Kevin; Feldpausch, Ted R.; Mitchard, Edward T. A.; Wani, Akhlaq A.; Joshi, Pawan K.
Abstract: Synthetic Aperture Radar (SAR) signals respond to the interactions of microwaves with vegetation canopy scatterers that collectively characterise forest structure. The sensitivity of S-band (7.5–15 cm) backscatter to the different forest types (broadleaved, needleleaved) with varying aboveground biomass (AGB) across temperate (mixed, needleleaved) and tropical (broadleaved, woody savanna, secondary) forests is less well understood. In this study, Michigan Microwave Canopy Scattering (MIMICS-I) radiative transfer model simulations showed strong volume scattering returns from S-band SAR for broadleaved canopies caused by ground/trunk interactions. A general relationship between AirSAR S-band measurements and MIMICS-I simulated radar backscatter with forest AGB up to nearly 100 t/ha in broadleaved forest in the UK was found. Simulated S-band backscatter-biomass relationships suggest increasing backscatter sensitivity to forest biomass with a saturation level close to 100 t/ha and errors between 37 t/ha and 44 t/ha for HV and VV polarisations for tropical ecosystems. In the near future, satellite SAR-derived forest biomass from P-band BIOMASS mission and L-band ALOS-2 PALSAR-2 in combination with S-band UK NovaSAR-S and the joint NASA-ISRO NISAR sensors will provide better quantification of large-scale forest AGB at varying sensitivity levels across primary and secondary forests and woody savannas.2018-01-09T15:18:47ZDrivers of metacommunity structure diverge for common and rare Amazonian tree species.Bispo, Polyanna da ConceiçãoBalzter, HeikoMalhi, YadvinderSlik, J. W. FerryDos Santos, João RobertoRennó, Camilo DalelesEspírito-Santo, Fernando D.Aragão, Luiz E. O. C.Ximenes, Arimatéa C.Bispo, Pitágoras da Conceiçãohttp://hdl.handle.net/2381/407832018-01-10T03:24:49Z2018-01-09T15:12:18ZTitle: Drivers of metacommunity structure diverge for common and rare Amazonian tree species.
Authors: Bispo, Polyanna da Conceição; Balzter, Heiko; Malhi, Yadvinder; Slik, J. W. Ferry; Dos Santos, João Roberto; Rennó, Camilo Daleles; Espírito-Santo, Fernando D.; Aragão, Luiz E. O. C.; Ximenes, Arimatéa C.; Bispo, Pitágoras da Conceição
Abstract: We analysed the flora of 46 forest inventory plots (25 m x 100 m) in old growth forests from the Amazonian region to identify the role of environmental (topographic) and spatial variables (obtained using PCNM, Principal Coordinates of Neighbourhood Matrix analysis) for common and rare species. For the analyses, we used multiple partial regression to partition the specific effects of the topographic and spatial variables on the univariate data (standardised richness, total abundance and total biomass) and partial RDA (Redundancy Analysis) to partition these effects on composition (multivariate data) based on incidence, abundance and biomass. The different attributes (richness, abundance, biomass and composition based on incidence, abundance and biomass) used to study this metacommunity responded differently to environmental and spatial processes. Considering standardised richness, total abundance (univariate) and composition based on biomass, the results for common species differed from those obtained for all species. On the other hand, for total biomass (univariate) and for compositions based on incidence and abundance, there was a correspondence between the data obtained for the total community and for common species. Our data also show that in general, environmental and/or spatial components are important to explain the variability in tree communities for total and common species. However, with the exception of the total abundance, the environmental and spatial variables measured were insufficient to explain the attributes of the communities of rare species. These results indicate that predicting the attributes of rare tree species communities based on environmental and spatial variables is a substantial challenge. As the spatial component was relevant for several community attributes, our results demonstrate the importance of using a metacommunities approach when attempting to understand the main ecological processes underlying the diversity of tropical forest communities.2018-01-09T15:12:18ZDrift-dependent changes in iceberg size-frequency distributionsKirkham, James D.Rosser, Nick J.Wainwright, JohnVann Jones, Emma C.Dunning, Stuart A.Lane, Victoria S.Hawthorn, David E.Strzelecki, Mateusz C.Szczuciński, Witoldhttp://hdl.handle.net/2381/407782018-01-10T03:24:41Z2018-01-09T14:09:42ZTitle: Drift-dependent changes in iceberg size-frequency distributions
Authors: Kirkham, James D.; Rosser, Nick J.; Wainwright, John; Vann Jones, Emma C.; Dunning, Stuart A.; Lane, Victoria S.; Hawthorn, David E.; Strzelecki, Mateusz C.; Szczuciński, Witold
Abstract: Although the size-frequency distributions of icebergs can provide insight into how they disintegrate, our understanding of this process is incomplete. Fundamentally, there is a discrepancy between iceberg power-law size-frequency distributions observed at glacial calving fronts and lognormal size-frequency distributions observed globally within open waters that remains unexplained. Here we use passive seismic monitoring to examine mechanisms of iceberg disintegration as a function of drift. Our results indicate that the shift in the size-frequency distribution of iceberg sizes observed is a product of fracture-driven iceberg disintegration and dimensional reductions through melting. We suggest that changes in the characteristic size-frequency scaling of icebergs can be explained by the emergence of a dominant set of driving processes of iceberg degradation towards the open ocean. Consequently, the size-frequency distribution required to model iceberg distributions accurately must vary according to distance from the calving front.
Description: Supplementary information accompanies this paper at https://doi.org/10.1038/s41598-017-14863-22018-01-09T14:09:42ZFrom Shiny Shoes to Muddy Reality: Understanding How Meso-State Actors Negotiate the Implementation Gap in Participatory Forest ManagementKairu, AnneUpton, CarolineHuxham, MarkKotut, KiplagatMbeche, RobertKairo, Jameshttp://hdl.handle.net/2381/407452018-01-09T03:30:14Z2018-01-08T16:30:09ZTitle: From Shiny Shoes to Muddy Reality: Understanding How Meso-State Actors Negotiate the Implementation Gap in Participatory Forest Management
Authors: Kairu, Anne; Upton, Caroline; Huxham, Mark; Kotut, Kiplagat; Mbeche, Robert; Kairo, James
Abstract: Recent research on participatory forest management (PFM) in the global south has highlighted the existence of a widespread “implementation gap” between the ambitious intent enshrined in legislation and the often partial, disappointing rollout of devolved forest governance on the ground. Here, through an ethnographic case study of forest officers (FOs) in Kenya, we draw on a framework of critical institutionalism to examine how key meso-level actors, or “interface bureaucrats,” negotiate and challenge this implementation gap in everyday forest governance. We go beyond consideration of institutional bricolage in isolation or as an aggregate category, to analyze how bricolage as aggregation, alteration, and/or articulation is variously driven, shaped, and constrained by FOs’ multiple accountabilities and agency. Our analysis highlights the locally specific, contingent, and mutually reinforcing nature of accountability, agency and bricolage, and their explanatory power in relation to the performance and nature of “actually existing” PFM.
Description: The file associated with this record is under embargo until 18 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.2018-01-08T16:30:09ZA Review on Remote Sensing of Urban Heat and Cool IslandsRasul, AzadBalzter, HeikoSmith, ClaireRemedios, JohnAdamu, BashirSobrino, Jose A.Srivanit, ManatWeng, Qihaohttp://hdl.handle.net/2381/405822017-11-24T03:22:46Z2017-11-23T10:48:54ZTitle: A Review on Remote Sensing of Urban Heat and Cool Islands
Authors: Rasul, Azad; Balzter, Heiko; Smith, Claire; Remedios, John; Adamu, Bashir; Sobrino, Jose A.; Srivanit, Manat; Weng, Qihao
Abstract: The variation between land surface temperature (LST) within a city and its surrounding area is a result of variations in surface cover, thermal capacity and three-dimensional geometry. The objective of this research is to review the state of knowledge and current research to quantify surface urban heat islands (SUHI) and surface urban cool islands (SUCI). In order to identify open issues and gaps remaining in this field, we review research on SUHI/SUCI, the models for simulating UHIs/UCIs and techniques used in this field were appraised. The appraisal has revealed some great progress made in surface UHI mapping of cities located in humid and vegetated (temperate) regions, whilst few studies have investigated the spatiotemporal variation of surface SUHI/SUCI and the effect of land use/land cover (LULC) change on LST in arid and semi-arid climates. While some progress has been made, models for simulating UHI/UCI have been advancing only slowly. We conclude and suggest that SUHI/SUCI in arid and semi-arid areas requires more in-depth study.2017-11-23T10:48:54ZTowards a study of information geographies: (im)mutable augmentations and a mapping of the geographies of informationGraham, MarkDe Sabbata, StefanoZook, Matthew A.http://hdl.handle.net/2381/405362017-11-17T03:23:48Z2017-11-16T11:12:08ZTitle: Towards a study of information geographies: (im)mutable augmentations and a mapping of the geographies of information
Authors: Graham, Mark; De Sabbata, Stefano; Zook, Matthew A.
Abstract: Information has always had geography. It is from somewhere; about somewhere; it evolves and is transformed
somewhere; it is mediated by networks, infrastructures, and technologies: all of which exist in physical, material
places. These geographies of information about places matter because they shape how we are able to find and
understand different parts of the world. Places invisible or discounted in representations are invisible in practice to
many people. In other words, geographic augmentations are much more than just representations of places: they
are part of the place itself; they shape it rather than simply reflect it. This fusing of the spatial and informational
augmentations that are immutable means that annotations of place emerge as sites of political contestation: with
different groups of people trying to impose different narratives on informational augmentations. This paper therefore
explores how information geographies have their own geographic distributions: geographies of access, of
participation, and of representation. The paper offers a deliberately broad survey of a range of key platforms that
mediate, host, and deliver different types of geographic information. It does so using a combination of existing
statistics and bespoke data not previously mapped or analysed. Through this effort, the paper demonstrates that in
addition to the geographies of uneven access to contemporary modes of communication, uneven geographies of
participation and representation are also evident and in some cases are being amplified rather than alleviated. In
other words, the paper comprehensively shows one important facet of contemporary information geographies: that
geographic information itself is characterised by a host of uneven geographies. The paper concludes that there are
few signs that global informational peripheries are achieving comparable levels of participation or representation with
traditional information cores, despite the hopes that the fast-paced spread of the internet to three billion people might change this pattern.2017-11-16T11:12:08ZReviews: Managers of Global Change: The Influence of International Environmental Bureaucracies, The Changing Governance of Renewable Natural Resources in Northwest Russia, Factor Five: Transforming the Global Economy through 80% Improvements in Resource Productivity, Governing the Tap: Special District Governance and the New Local Politics of WaterPark, SusanBradshaw, MichaelWilson, CharlieBrowne, Alisonhttp://hdl.handle.net/2381/404562017-11-01T03:23:00Z2017-10-31T14:20:19ZTitle: Reviews: Managers of Global Change: The Influence of International Environmental Bureaucracies, The Changing Governance of Renewable Natural Resources in Northwest Russia, Factor Five: Transforming the Global Economy through 80% Improvements in Resource Productivity, Governing the Tap: Special District Governance and the New Local Politics of Water
Authors: Park, Susan; Bradshaw, Michael; Wilson, Charlie; Browne, Alison
Abstract: [First paragraph] Ever wondered how the environmental convention secretariats operate? Or how and why the
Organisation on Economic Cooperation and Development (OECD) created an environment
directorate? Many of these bureaucracies have not been studied in great detail precisely because
they fit within the broader debate over the power and effectiveness of environmental regimes.
This volume investigates four environmental convention secretariats (climate, ozone, desertification,
and biodiversity), the secretariats for the International Maritime Organisation (IMO),
the Global Environment Facility (GEF), the United Nations Environment Program, and the environmental
units of the World Bank and the OECD. Frank Biermann and Bernd Siebenhu«ner's
collection is the result of a four-year ``Managers of global change: effectiveness and learning of
international organisations'' research program2017-10-31T14:20:19ZTree height strongly affects estimates of water-use efficiency responses to climate and CO2 using isotopesBrienen, R. J. W.Gloor, E.Clerici, S.Newton, R.Arppe, L.Boom, ArnoudBottrell, S.Callaghan, M.Heaton, T.Helama, S.Helle, G.Leng, M. J.Mielikäinen, K.Oinonen, M.Timonen, M.http://hdl.handle.net/2381/404142017-10-03T02:22:30Z2017-10-02T15:11:45ZTitle: Tree height strongly affects estimates of water-use efficiency responses to climate and CO2 using isotopes
Authors: Brienen, R. J. W.; Gloor, E.; Clerici, S.; Newton, R.; Arppe, L.; Boom, Arnoud; Bottrell, S.; Callaghan, M.; Heaton, T.; Helama, S.; Helle, G.; Leng, M. J.; Mielikäinen, K.; Oinonen, M.; Timonen, M.
Abstract: Various studies report substantial increases in intrinsic water-use efficiency (W i ), estimated using carbon isotopes in tree rings, suggesting trees are gaining increasingly more carbon per unit water lost due to increases in atmospheric CO2. Usually, reconstructions do not, however, correct for the effect of intrinsic developmental changes in W i as trees grow larger. Here we show, by comparing W i across varying tree sizes at one CO2 level, that ignoring such developmental effects can severely affect inferences of trees’ W i . W i doubled or even tripled over a trees’ lifespan in three broadleaf species due to changes in tree height and light availability alone, and there are also weak trends for Pine trees. Developmental trends in broadleaf species are as large as the trends previously assigned to CO2 and climate. Credible future tree ring isotope studies require explicit accounting for species-specific developmental effects before CO2 and climate effects are inferred.2017-10-02T15:11:45ZGeodemographic biases in crowdsourced knowledge websites: Do neighbours fill in the blanks?Bright, JonathanDe Sabbata, StefanoLee, Suminhttp://hdl.handle.net/2381/403832017-09-21T02:22:21Z2017-09-20T10:48:28ZTitle: Geodemographic biases in crowdsourced knowledge websites: Do neighbours fill in the blanks?
Authors: Bright, Jonathan; De Sabbata, Stefano; Lee, Sumin
Abstract: Crowdsourced knowledge websites such as Wikipedia and OpenStreetMap are increasingly attracting a critical literature which has highlighted the fact that the contributor bases of these sites are often geodemographically biased: drawn from more affluent and better educated segments of the population. However, while bias in contributors is well known, we know less about whether this also results in a bias in outcomes on these websites: or whether the partial portion of the population which does make contributions also works to “fill in the blanks”, by adding knowledge about other less well-off neighbouring areas which have not attracted a contributor base. This article addresses the question of whether such “neighbourhood effects” exist in practice. It makes use of a novel dataset of alcohol license data in the UK to assess variation in the completeness of the volunteer geographic information site OpenStreetMap. The results support existing literature in showing that completeness is related to demographics: areas with higher levels of wealth and education typically exhibit higher levels of completeness. The article then makes a novel contribution by showing evidence of the existence of neighbourhood effects: poorer regions with more affluent neighbours typically having higher levels of completeness than poorer regions which are also surrounded by poorer neighbours. The results suggest that crowdsourced knowledge websites can aspire to a kind of completeness even whilst user bases remain partial and biased.2017-09-20T10:48:28ZBiodiversity detectives!Balzter, HeikoBarnes, ChloeFillingham, JanetBoot, Kelvinhttp://hdl.handle.net/2381/403642017-09-13T02:23:41Z2017-09-12T14:52:21ZTitle: Biodiversity detectives!
Authors: Balzter, Heiko; Barnes, Chloe; Fillingham, Janet; Boot, Kelvin
Description: The file associated with this record is under embargo while permission to archive is sought from the publisher. The full text may be available through the publisher links provided above.2017-09-12T14:52:21ZEstimating daily reference evapotranspiration in a semi-arid region using remote sensing dataNajmaddin, Peshawa M.Whelan, Mick J.Balzter, Heikohttp://hdl.handle.net/2381/403262017-09-06T02:26:02Z2017-09-05T14:40:50ZTitle: Estimating daily reference evapotranspiration in a semi-arid region using remote sensing data
Authors: Najmaddin, Peshawa M.; Whelan, Mick J.; Balzter, Heiko
Abstract: Estimating daily evapotranspiration is challenging when ground observation data are not available or scarce. Remote sensing can be used to estimate the meteorological data necessary for calculating reference evapotranspiration ETₒ. Here, we assessed the accuracy of daily ETₒ estimates derived from remote sensing (ETₒ-RS) compared with those derived from four ground-based stations (ETₒ-G) in Kurdistan (Iraq) over the period 2010–2014. Near surface air temperature, relative humidity and cloud cover fraction were derived from the Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit (AIRS/AMSU), and wind speed at 10 m height from MERRA (Modern-Era Retrospective Analysis for Research and Application). Four methods were used to estimate ETₒ: Hargreaves–Samani (HS), Jensen–Haise (JH), McGuinness–Bordne (MB) and the FAO Penman Monteith equation (PM). ETₒ-G (PM) was adopted as the main benchmark. HS underestimated ETₒ by 2%–3% (R2 = 0.86 to 0.90; RMSE = 0.95 to 1.2 mm day−1 at different stations). JH and MB overestimated ETₒ by 8% to 40% (R2= 0.85 to 0.92; RMSE from 1.18 to 2.18 mm day−1). The annual average values of ETₒ estimated using RS data and ground-based data were similar to one another reflecting low bias in daily estimates. They ranged between 1153 and 1893 mm year−1 for ETₒ-G and between 1176 and 1859 mm year−1 for ETₒ-RS for the different stations. Our results suggest that ETₒ-RS (HS) can yield accurate and unbiased ETₒ estimates for semi-arid regions which can be usefully employed in water resources management.2017-09-05T14:40:50ZSeasonal variability in methane and nitrous oxide fluxes from tropical peatlands in the western Amazon basinTeh, Yit ArnMurphy, Wayne A.Berrio, Juan-CarlosBoom, ArnoudPage, Susan E.http://hdl.handle.net/2381/403032017-09-02T02:29:52Z2017-09-01T15:43:25ZTitle: Seasonal variability in methane and nitrous oxide fluxes from tropical peatlands in the western Amazon basin
Authors: Teh, Yit Arn; Murphy, Wayne A.; Berrio, Juan-Carlos; Boom, Arnoud; Page, Susan E.
Abstract: The Amazon plays a critical role in global atmospheric budgets of methane (CH4) and nitrous oxide (N2O). However, while we have a relatively good understanding of the continental-scale flux of these greenhouse gases (GHGs), one of the key gaps in knowledge is the specific contribution of peatland ecosystems to the regional budgets of these GHGs. Here we report CH4 and N2O fluxes from lowland tropical peatlands in the Pastaza–Marañón foreland basin (PMFB) in Peru, one of the largest peatland complexes in the Amazon basin. The goal of this research was to quantify the range and magnitude of CH4 and N2O fluxes from this region, assess seasonal trends in trace gas exchange, and determine the role of different environmental variables in driving GHG flux. Trace gas fluxes were determined from the most numerically dominant peatland vegetation types in the region: forested vegetation, forested (short pole) vegetation, Mauritia flexuosa-dominated palm swamp, and mixed palm swamp. Data were collected in both wet and dry seasons over the course of four field campaigns from 2012 to 2014. Diffusive CH4 emissions averaged 36.05 ± 3.09 mg CH4–C m−2 day−1 across the entire dataset, with diffusive CH4 flux varying significantly among vegetation types and between seasons. Net ebullition of CH4 averaged 973.3 ± 161.4 mg CH4–C m−2 day−1 and did not vary significantly among vegetation types or between seasons. Diffusive CH4 flux was greatest for mixed palm swamp (52.0 ± 16.0 mg CH4–C m−2 day−1), followed by M. flexuosa palm swamp (36.7 ± 3.9 mg CH4–C m−2 day−1), forested (short pole) vegetation (31.6 ± 6.6 mg CH4–C m−2 day−1), and forested vegetation (29.8 ± 10.0 mg CH4–C m−2 day−1). Diffusive CH4 flux also showed marked seasonality, with divergent seasonal patterns among ecosystems. Forested vegetation and mixed palm swamp showed significantly higher dry season (47.2 ± 5.4 mg CH4–C m−2 day−1 and 85.5 ± 26.4 mg CH4–C m−2 day−1, respectively) compared to wet season emissions (6.8 ± 1.0 mg CH4–C m−2 day−1 and 5.2 ± 2.7 mg CH4–C m−2 day−1, respectively). In contrast, forested (short pole) vegetation and M. flexuosa palm swamp showed the opposite trend, with dry season flux of 9.6 ± 2.6 and 25.5 ± 2.9 mg CH4–C m−2 day−1, respectively, versus wet season flux of 103.4 ± 13.6 and 53.4 ± 9.8 mg CH4–C m−2 day−1, respectively. These divergent seasonal trends may be linked to very high water tables (> 1 m) in forested vegetation and mixed palm swamp during the wet season, which may have constrained CH4 transport across the soil–atmosphere interface. Diffusive N2O flux was very low (0.70 ± 0.34 µg N2O–N m−2 day−1) and did not vary significantly among ecosystems or between seasons. We conclude that peatlands in the PMFB are large and regionally significant sources of atmospheric CH4 that need to be better accounted for in regional emissions inventories. In contrast, N2O flux was negligible, suggesting that this region does not make a significant contribution to regional atmospheric budgets of N2O. The divergent seasonal pattern in CH4 flux among vegetation types challenges our underlying assumptions of the controls on CH4 flux in tropical peatlands and emphasizes the need for more process-based measurements during periods of high water table.
Description: These data are publicly available through the
UK Natural Environment Research Council’s (NERC) Centre for
Environmental Data Analysis (CEDA), with DOI http://dx.doi.org/
10.5072/a3614fb00ff74999a5187d3a3767d96d.
The Supplement related to this article is available online
at https://doi.org/10.5194/bg-14-3669-2017-supplement.2017-09-01T15:43:25ZEngagement in the Knowledge Economy: Regional Patterns of Content Creation with a Focus on Sub-Saharan AfricaDe Sabbata, SOjanperä, SGraham, MStraumann, Rhttp://hdl.handle.net/2381/400792017-07-14T02:22:29Z2017-07-13T09:25:28ZTitle: Engagement in the Knowledge Economy: Regional Patterns of Content Creation with a Focus on Sub-Saharan Africa
Authors: De Sabbata, S; Ojanperä, S; Graham, M; Straumann, R
Abstract: Increasing digital connectivity has sparked many hopes for the democratization of information and knowledge production in sub-Saharan Africa. To investigate the patterns of knowledge creation in the region compared to other world regions, we examine three key metrics: spatial distributions of academic articles (traditional knowledge production), collaborative software development, and Internet domain registrations (digitally mediated knowledge production). We find that, contrary to the expectation that digital content is more evenly geographically distributed than academic articles, the global and regional patterns of collaborative coding and domain registrations are more uneven than those of academic articles. Despite hopes for democratization afforded by the information revolution, sub-Saharan Africa produces a smaller share of digital content than academic articles. Our results suggest the factors often framed as catalysts in the transformation into a knowledge economy do not relate to the three metrics uniformly. While connectivity is an important enabler of digital content creation, it seems to be only a necessary, not a sufficient, condition; wealth, innovation capacity, and public spending on education are also important factors.2017-07-13T09:25:28ZHijacking the Narrative: The First World Forum on Natural Capital, #natcap13, and Radical DissentMatulis, Brett S.Moyer, Jessica R.http://hdl.handle.net/2381/400722017-07-13T02:22:40Z2017-07-12T13:51:27ZTitle: Hijacking the Narrative: The First World Forum on Natural Capital, #natcap13, and Radical Dissent
Authors: Matulis, Brett S.; Moyer, Jessica R.
Abstract: The first World Forum on Natural Capital (WFNC) was an important moment in the production of “valued” nature. It brought together bankers, CEOs, and business elites to promote financialized environmental accounting as a solution to ecosystem degradation. Anti-capitalist activists, however, opposed the further intrusion of economic logic to environmental decision-making and resisted its progression. While WFNC organizers were able to advance the concept of “natural capital” through traditional (print and web 1.0) media, they struggled to control the social media narrative. Digital activists were able to challenge the official narrative on Twitter and compel organizers to address the associated social and environmental justice concerns. As such, social media produced the conditions for both abstracting nature into value-bearing commodities and, simultaneously, resisting such abstraction. Drawing on theories of counterpublic organization, public spheres of deliberation, and agonistic confrontation, this paper explores the discursive co-production of nature in a new digitally mediated world.
Description: The file associated with this record is under embargo until 24 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.2017-07-12T13:51:27ZConnecting Earth Observation to High-Throughput Biodiversity DataBush, A.Sollmann, R.Wilting, A.Bohmann, K.Cole, BethBalzter, HeikoMartius, C.Zlinszky, A.Calvignac-Spencer, S.Cobbold, C.Dawson, T.Emerson, B.Ferrier, S.Gilbert, M. T.Herold, M.Jones, L.Leendertz, F.Matthews, L.Millington, J.Olson, J.Ovaskainen, O.Raffaelli, D.Reeve, R.Rödel, M.-O.Rodgers, T.Snape, S.Visseren-Hamakers, I.Vogler, A. P.White, P.Wooster, M.Yu, D.http://hdl.handle.net/2381/400142017-12-22T02:45:07Z2017-07-06T15:38:40ZTitle: Connecting Earth Observation to High-Throughput Biodiversity Data
Authors: Bush, A.; Sollmann, R.; Wilting, A.; Bohmann, K.; Cole, Beth; Balzter, Heiko; Martius, C.; Zlinszky, A.; Calvignac-Spencer, S.; Cobbold, C.; Dawson, T.; Emerson, B.; Ferrier, S.; Gilbert, M. T.; Herold, M.; Jones, L.; Leendertz, F.; Matthews, L.; Millington, J.; Olson, J.; Ovaskainen, O.; Raffaelli, D.; Reeve, R.; Rödel, M.-O.; Rodgers, T.; Snape, S.; Visseren-Hamakers, I.; Vogler, A. P.; White, P.; Wooster, M.; Yu, D.
Abstract: Understandably, given the fast pace of biodiversity loss, there is much interest in using Earth observation technology to track biodiversity, ecosystem functions and ecosystem services. However, because most biodiversity is invisible to Earth observation, indicators based on Earth observation could be misleading and reduce the effectiveness of nature conservation and even unintentionally decrease conservation effort. We describe an approach that combines automated recording devices, high-throughput DNA sequencing and modern ecological modelling to extract much more of the information available in Earth observation data. This approach is achievable now, offering efficient and near-real-time monitoring of management impacts on biodiversity and its functions and services.
Description: The file associated with this record is under embargo until 6 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.2017-07-06T15:38:40ZApplication of Satellite-Based Precipitation Estimates to Rainfall-Runoff Modelling in a Data-Scarce Semi-Arid CatchmentNajmaddin, Peshawa M.Whelan, Mick J.Balzter, Heikohttp://hdl.handle.net/2381/399962017-07-06T02:23:30Z2017-07-05T14:16:44ZTitle: Application of Satellite-Based Precipitation Estimates to Rainfall-Runoff Modelling in a Data-Scarce Semi-Arid Catchment
Authors: Najmaddin, Peshawa M.; Whelan, Mick J.; Balzter, Heiko
Abstract: Rainfall-runoff modelling is a useful tool for water resources management. This study presents a simple daily rainfall-runoff model, based on the water balance equation, which we apply to the 11,630 km2 Lesser Zab catchment in northeast Iraq. The model was forced by either observed daily rain gauge data from four stations in the catchment or satellite-derived rainfall estimates from two TRMM Multi-satellite Precipitation Analysis (TMPA) data products (TMPA-3B42 and 3B42RT) based on the Tropical Rainfall Measuring Mission (TRMM) from 2003 to 2014. As well as using raw TMPA data, we used a bias-correction method to adjust TMPA values based on rain gauge data. The uncorrected TMPA data products underestimated observed mean catchment rainfall by −10.1% and −10.7%. Corrected data also slightly underestimated gauged rainfall by −0.7% and −1.6%, respectively. Nash-Sutcliffe Efficiency (NSE) and Pearson’s Correlation Coefficient (r) for the model fit with the observed hydrograph were 0.75 and 0.87, respectively, for a calibration period (2010–2011) using gauged rainfall data. Model validation performance (2012–2014) was best (highest NSE and r; lowest RMSE and bias) using the corrected 3B42 data product and poorest when driven by uncorrected 3B42RT data. Uncertainty and equifinality were also explored. Our results suggest that TRMM data can be used to drive rainfall-runoff modelling in semi-arid catchments, particularly when corrected using rain gauge data.
Description: Supplementary Materials: The following are available online at www.mdpi.com/2225-1154/5/2/32/s1.2017-07-05T14:16:44ZExtrapolating Forest Canopy Fuel Properties in the California Rim Fire by Combining Airborne LiDAR and Landsat OLI DataGarcía, MarianoSaatchi, SassanCasas, AngelesKoltunov, AlexanderUstin, Susan L.Ramirez, CarlosBalzter, Heikohttp://hdl.handle.net/2381/399662017-06-28T02:21:15Z2017-06-27T15:28:38ZTitle: Extrapolating Forest Canopy Fuel Properties in the California Rim Fire by Combining Airborne LiDAR and Landsat OLI Data
Authors: García, Mariano; Saatchi, Sassan; Casas, Angeles; Koltunov, Alexander; Ustin, Susan L.; Ramirez, Carlos; Balzter, Heiko
Abstract: Accurate, spatially explicit information about forest canopy fuel properties is essential for ecosystem management strategies for reducing the severity of forest fires. Airborne LiDAR technology has demonstrated its ability to accurately map canopy fuels. However, its geographical and temporal coverage is limited, thus making it difficult to characterize fuel properties over large regions before catastrophic events occur. This study presents a two-step methodology for integrating post-fire airborne LiDAR and pre-fire Landsat OLI (Operational Land Imager) data to estimate important pre-fire canopy fuel properties for crown fire spread, namely canopy fuel load (CFL), canopy cover (CC), and canopy bulk density (CBD). This study focused on a fire prone area affected by the large 2013 Rim fire in the Sierra Nevada Mountains, California, USA. First, LiDAR data was used to estimate CFL, CC, and CBD across an unburned 2 km buffer with similar structural characteristics to the burned area. Second, the LiDAR-based canopy fuel properties were extrapolated over the whole area using Landsat OLI data, which yielded an R2 of 0.8, 0.79, and 0.64 and RMSE of 3.76 Mg·ha−1, 0.09, and 0.02 kg·m−3 for CFL, CC, and CBD, respectively. The uncertainty of the estimates was estimated for each pixel using a bootstrapping approach, and the 95% confidence intervals are reported. The proposed methodology provides a detailed spatial estimation of forest canopy fuel properties along with their uncertainty that can be readily integrated into fire behavior and fire effects models. The methodology could be also integrated into the LANDFIRE program to improve the information on canopy fuels.2017-06-27T15:28:38ZLeonard Horner and an enthusiasm for Loess. [Leicester Studies in the History of Loess Research part I]Smalley, IanKels, Holgerhttp://hdl.handle.net/2381/398042017-05-18T02:21:57Z2017-05-17T13:49:44ZTitle: Leonard Horner and an enthusiasm for Loess. [Leicester Studies in the History of Loess Research part I]
Authors: Smalley, Ian; Kels, Holger
Abstract: Leonard Horner (1785-1864) made substantial contributions to the study of loess. He made field trips with J.J. Noeggerath and Charles Lyell and published useful material on the loess near Bonn. He was an unappreciated pioneer- he was the first person to direct attention to loess as a material. He pointed out that loess was intrinsically interesting. He studied the material transported by the Rhine, and the alluvial deposits in Egypt, looking for links to loess, and the problem of loess formation. He was born in Edinburgh in 1785 and directed the thoughts of young Charles Darwin towards science when he came to Edinburgh to study medicine. Circumstances placed him in Bonn in the critical years 1831-1833; in this time Charles Lyell married his eldest daughter Mary; and both Lyell and Horner encountered the loess. Lyell made it well known via vol.3 of the Principles of Geology, Horner became a loess enthusiast. In the summer of 1833 Horner & Lyell were in the crater of the Roderberg considering the more than 20. m of loess deposited there. His major paper was published in 1836 (reporting the Roderberg excursion) and he joined Lyell's list of loess investigators in the 5th edition of the Principles published in 1837. He was the last to join that select eleven: Bronn, Leonhard, Boue, Voltz, Steininger, Merian, Rozet, Hibbert, Noeggerath, von Meyer, Horner. Most of these were writing on the geology and landscapes of the Rhine valley, but Horner was drawing attention to the amazing nature of the loess itself, in particular the spectacular disaggregation on contact with water. He also published the first geological map of the Bonn region, including the Roderberg and the Siebengebirge, a region of loess and volcanoes.
Description: The file associated with this record is embargoed until 12 months after the date of publication. The final published version may be available through the links above.2017-05-17T13:49:44ZA quantitative analysis of global gazetteers: Patterns of coverage for common feature typesAcheson, EliseDe Sabbata, StefanoPurves, Rosshttp://hdl.handle.net/2381/397692017-05-13T03:13:48Z2017-05-12T13:43:56ZTitle: A quantitative analysis of global gazetteers: Patterns of coverage for common feature types
Authors: Acheson, Elise; De Sabbata, Stefano; Purves, Ross
Abstract: Gazetteers are important tools used in a wide variety of workflows that depend on linking natural language text to geographical space. The spatial properties of these data sources, such as coverage, balance, and completeness, affect the performance of common tasks such as geoparsing and geocoding. However, little attention has focused on how these properties vary in global gazetteers, particularly across country boundaries and according to feature types. In this paper, we present a detailed investigation of the spatial properties of two open gazetteers with worldwide coverage: GeoNames, and the Getty Thesaurus of Geographic Names (TGN). Using point density maps, correlations, and linear regressions, we analyze the global spatial coverage of each data source for the full set of features and for top feature types: populated places, streams, mountains, and hills. Results show wide discrepancies in coverage between the two datasets, sharp changes in feature type coverage across country borders, and idiosyncratic patterns dominated by a few countries for the more sparsely covered natural features. As more and more systems rely on recognizing and grounding named places, these patterns can influence the analysis of growing amounts of online text content and reinforce or amplify existing inequalities.2017-05-12T13:43:56ZFrom carbon sink to carbon source: extensive peat oxidation in insular Southeast Asia since 1990Miettinen, JukkaHooijer, AljosjaVernimmen, RonaldLiew, Soo ChinPage, Susan E.http://hdl.handle.net/2381/397582017-05-11T02:22:44Z2017-05-10T14:32:16ZTitle: From carbon sink to carbon source: extensive peat oxidation in insular Southeast Asia since 1990
Authors: Miettinen, Jukka; Hooijer, Aljosja; Vernimmen, Ronald; Liew, Soo Chin; Page, Susan E.
Abstract: Tropical peatlands of the western part of insular Southeast Asia have experienced extensive land cover changes since 1990. Typically involving drainage, these land cover changes have resulted in increased peat oxidation in the upper peat profile. In this paper we provide current (2015) and cumulative carbon emissions estimates since 1990 from peat oxidation in Peninsular Malaysia, Sumatra and Borneo, utilizing newly published peatland land cover information and the recently agreed Intergovernmental Panel on Climate Change (IPCC) peat oxidation emission values for tropical peatland areas. Our results highlight the change of one of the Earth's most efficient long-term carbon sinks to a short-term emission source, with cumulative carbon emissions since 1990 estimated to have been in the order of 2.5 Gt C. Current (2015) levels of emissions are estimated at around 146 Mt C yr-1, with a range of 132-159 Mt C yr-1 depending on the selection of emissions factors for different land cover types. 44% (or 64 Mt C yr-1) of the emissions come from industrial plantations (mainly oil palm and Acacia pulpwood), followed by 34% (49 Mt C yr-1) of emissions from small-holder areas. Thus, altogether 78% of current peat oxidation emissions come from managed land cover types. Although based on the latest information, these estimates may still include considerable, yet currently unquantifiable, uncertainties (e.g. due to uncertainties in the extent of peatlands and drainage networks) which need to be focused on in future research. In comparison, fire induced carbon dioxide emissions over the past ten years for the entire equatorial Southeast Asia region have been estimated to average 122 Mt C yr-1 (www.globalfiredata.org/-index.html). The results emphasise that whilst reducing emissions from peat fires is important, urgent efforts are also needed to mitigate the constantly high level of emissions arising from peat drainage, regardless of fire occurrence.2017-05-10T14:32:16ZAlternative glacial-interglacial refugia demographic hypotheses tested on Cephalocereus columna-trajani (Cactaceae) in the intertropical Mexican drylandsCornejo-Romero, AmeliaVargas-Mendoza, Carlos FabiánAguilar-Martínez, Gustavo F.Medina-Sánchez, JavierRendón-Aguilar, BeatrizValverde, Pedro LuisZavala-Hurtado, Jose AlejandroSerrato, AlejandraRivas-Arancibia, SombraPérez-Hernández, Marco AurelioLópez-Ortega, GerardoJiménez-Sierra, Ceciliahttp://hdl.handle.net/2381/397022017-04-27T02:21:36Z2017-04-26T10:38:18ZTitle: Alternative glacial-interglacial refugia demographic hypotheses tested on Cephalocereus columna-trajani (Cactaceae) in the intertropical Mexican drylands
Authors: Cornejo-Romero, Amelia; Vargas-Mendoza, Carlos Fabián; Aguilar-Martínez, Gustavo F.; Medina-Sánchez, Javier; Rendón-Aguilar, Beatriz; Valverde, Pedro Luis; Zavala-Hurtado, Jose Alejandro; Serrato, Alejandra; Rivas-Arancibia, Sombra; Pérez-Hernández, Marco Aurelio; López-Ortega, Gerardo; Jiménez-Sierra, Cecilia
Abstract: Historic demography changes of plant species adapted to New World arid environments could be consistent with either the Glacial Refugium Hypothesis (GRH), which posits that populations contracted to refuges during the cold-dry glacial and expanded in warm-humid interglacial periods, or with the Interglacial Refugium Hypothesis (IRH), which suggests that populations contracted during interglacials and expanded in glacial times. These contrasting hypotheses are developed in the present study for the giant columnar cactus Cephalocereus columna-trajani in the intertropical Mexican drylands where the effects of Late Quaternary climatic changes on phylogeography of cacti remain largely unknown. In order to determine if the historic demography and phylogeographic structure of the species are consistent with either hypothesis, sequences of the chloroplast regions psbA-trnH and trnT-trnL from 110 individuals from 10 populations comprising the full distribution range of this species were analysed. Standard estimators of genetic diversity and structure were calculated. The historic demography was analysed using a Bayesian approach and the palaeodistribution was derived from ecological niche modelling to determine if, in the arid environments of south-central Mexico, glacial-interglacial cycles drove the genetic divergence and diversification of this species. Results reveal low but statistically significant population differentiation (FST = 0.124, P < 0.001), although very clear geographic clusters are not formed. Genetic diversity, haplotype network and Approximate Bayesian Computation (ABC) demographic analyses suggest a population expansion estimated to have taken place in the Last Interglacial (123.04 kya, 95% CI 115.3–130.03). The species palaeodistribution is consistent with the ABC analyses and indicates that the potential area of palaedistribution and climatic suitability were larger during the Last Interglacial and Holocene than in the Last Glacial Maximum. Overall, these results suggest that C. columna-trajani experienced an expansion following the warm conditions of interglacials, in accordance with the GRH.
Description: Data are available from NCBI GenBank database (accession numbers KY363333-KY363338).2017-04-26T10:38:18Z(Re)Connecting spatial literacy with children's geographies: GPS, Google Earth and children's everyday livesJarvis, Claire H.Kraftl, P.Dickie, J.http://hdl.handle.net/2381/396972017-04-26T02:22:29Z2017-04-25T11:27:39ZTitle: (Re)Connecting spatial literacy with children's geographies: GPS, Google Earth and children's everyday lives
Authors: Jarvis, Claire H.; Kraftl, P.; Dickie, J.
Abstract: This article sets out an agenda for research that (re)connects research on children's geographies and childhood studies with studies of spatial literacy. Research on children's environmental cognition and, latterly, spatial literacy, has been artificially and problematically separated from the majority of research in childhood studies. Our fundamental aim in this article is to argue for – and to evidence – greater attention to how spatial literacy and children's everyday lives are embedded in one another. To support our broader call for a synthetic research agenda, we draw on some more focussed, qualitative empirical material taken from a large-scale project about children's mobilities and everyday lives in newly-built urban communities. Our analysis focuses upon children's interpretations of Global Positioning Systems (GPS) tracks of their mobilities, set against a background of Google Earth imagery. In doing so, we showcase one suite of ways in which research on environmental cognition and children's geographies might proceed together. We demonstrate that children not only displayed analytical skills (for instance, in relation to scaling effects and pattern recognition) but that many also exercised higher-level, critical analysis, especially in relation to errors on Google Earth outputs. Simultaneously, we interrogate the recursive articulation of a range of qualitative indicators of spatial literacy, with children's everyday mobilities, routines, emotions and memories. The paper analyses how new conceptual languages and technologies being propounded by spatial literacy scholars could afford a more enriched understanding of key contemporary concerns for children's geographers, and, recursively, what spatial literacy scholars might gain from engaging with (especially qualitative) research prompted by those concerns.
Description: The file associated with this record is embargoed until 24 months after the date of publication. The final published version may be available through the links above.2017-04-25T11:27:39ZHydrogen isotope fractionation of leaf wax n-alkanes in southern African soilsHerrmann, NicoleBoom, ArnoudCarr, Andrew S.Chase, Brian M.West, Adam G.Zabel, MatthiasSchefuss, Ennohttp://hdl.handle.net/2381/396782017-04-22T03:08:20Z2017-04-21T10:42:16ZTitle: Hydrogen isotope fractionation of leaf wax n-alkanes in southern African soils
Authors: Herrmann, Nicole; Boom, Arnoud; Carr, Andrew S.; Chase, Brian M.; West, Adam G.; Zabel, Matthias; Schefuss, Enno
Abstract: The hydrogen isotope composition of plant leaf wax (δDwax) has been found to record the isotope composition of precipitation (δDp). Hence, δDwax is increasingly used for palaeohydrological reconstruction. δDwax is, however, also affected by secondary factors, such as vegetation type, evapotranspiration and environmental conditions, complicating its direct application as a quantitative palaeohydrological proxy. Here, we present δDwax data from soils along vegetation gradients and climatic transects in southern Africa to investigate the impact of different environmental factors on δDwax. We found that δDwax correlated significantly with annual δDp (obtained from the interpolated Online Isotopes in Precipitation Calculator data set) throughout the eastern and central South Africa, where the majority of the mean annual precipitation falls during the summer. We found evidence for the effect of evapotranspiration on δDwax, while vegetation change was of minor importance. In contrast, we found that δDwax did not correlate with annual δDp in western and southwestern South Africa, where most of the annual precipitation falls during winter. Wide microclimatic variability in this topographical variable region, including distinct vegetation communities and high vegetation diversity between biomes as well as a potential influence of summer rain in some locals, likely compromised identification of a clear relationship between δDwax and δDp in this region. Our findings have implications for palaeoenvironmental investigations using δDwax in southern Africa. In the summer rain dominated eastern and central region, δDwax should serve well as a qualitative palaeohydrological recorder. In contrast, the processes influencing δDwax in the winter rain dominated western and southwestern South Africa remain unclear and pending further analyses potentially constrain its use as palaeohydrological proxy in this region.
Description: The file associated with this record is embargoed until 18 months after the date of publication. The final published version may be available through the links above. Following the embargo period the above license applies.2017-04-21T10:42:16ZAnalyzing the Impacts of Urbanization and Seasonal Variation on Land Surface Temperature Based on Subpixel Fractional Covers Using Landsat ImagesZhang, YoushuiBalzter, HeikoLiu, BinChen, Yajunhttp://hdl.handle.net/2381/395882017-03-28T02:22:05Z2017-03-27T14:52:15ZTitle: Analyzing the Impacts of Urbanization and Seasonal Variation on Land Surface Temperature Based on Subpixel Fractional Covers Using Landsat Images
Authors: Zhang, Youshui; Balzter, Heiko; Liu, Bin; Chen, Yajun
Abstract: Impervious surface areas (ISAs) and vegetation are two major urban land cover types. Estimating the spatial distribution of ISA and vegetation is critical for analyzing urban landscape patterns and their impact on the thermal environment. In this paper, linear spectral mixture analysis (LSMA) is used to extract their respective subpixel land cover composition from bitemporal Landsat images and the accuracy of the fractional covers is assessed with a subpixel confusion matrix at the category level and the map level by comparing with the reference data from high-resolution images. The percent ISA was divided into discrete categories representing different urban development density areas. Mean land surface temperature (LST) is calculated for each ISA category to analyze the thermal characteristics of different levels of development in the urban area of Fuzhou, China. ISA and vegetation variations are also quantified between different ISA categories and different dates. The contribution index is also calculated based on each ISA category to analyze the impact of different landscape patterns on the urban thermal environment. The results show that ISA category is an important determinant of the urban thermal environment. Furthermore, seasonal variations significantly impact the strength of this relationship. In the study area, the contribution indices were highest in the 90%–100% ISA category in summer 2013 and early spring 2001. The analytical methodologies used in this study can help to quantify urban thermal environmental functions under conditions of urban expansion and explore the climate adaptation potential of cities.2017-03-27T14:52:15ZMulti-Criteria Assessment of Land Cover Dynamic Changes in Halgurd Sakran National Park (HSNP), Kurdistan Region of Iraq, Using Remote Sensing and GISHamad, RahelBalzter, HeikoKolo, Kamalhttp://hdl.handle.net/2381/395832017-03-28T02:22:07Z2017-03-27T14:01:24ZTitle: Multi-Criteria Assessment of Land Cover Dynamic Changes in Halgurd Sakran National Park (HSNP), Kurdistan Region of Iraq, Using Remote Sensing and GIS
Authors: Hamad, Rahel; Balzter, Heiko; Kolo, Kamal
Abstract: Halgurd Sakran National Park (HSNP) is Iraq’s first designated national park, located in the Kurdistan Region, which has suffered multiple armed conflicts over the past decades. This study assesses how vegetation dynamics have affected the landscape structure and composition of the core zone of the park over the last 31 years. Spatio-temporal changes in land cover were mapped for three points in time using remote sensing, geographic information systems (GIS), and landscape metrics. Land cover changes were mapped using random forest classifications of satellite images from Landsat 5 TM, Landsat 7 ETM+, and Landsat 8 LDCM acquired in 1984, 1998, and 2015. Five landscape pattern metrics were analysed at class and landscape levels in order to quantify landscape patterns arising from land use and land cover (LULC) change in HSNP using FRAGSTATS 4.2. These landscape pattern metrics were patch metrics, area metrics, shape metrics interspersion/juxtaposition and contagion metrics and diversity metrics. Significant changes in cultivated areas after 1991 were observed, which indicate the role of anthropogenic activities in land cover change. Areas of bare surface and forest lands declined and became more fragmented in 1984 and 1998 while, at the same time, cultivated areas increased, with a continuing fragmentation of pasture land. Internal migration of people was one of the major drivers of LULC change. The results reveal that significant LULC changes in terms of composition and spatial structure over the 31-year period have occurred in the designated protected area. Landscape metrics were able to assess the trend of spatial patchiness over the studied period. A discussion of the significance of changes in land use systems for understanding the causes and consequences of change is provided.2017-03-27T14:01:24ZIndividual Tree Crown Delineation from Airborne Laser Scanning for Diseased Larch Forest StandsBarnes, ChloeBalzter, HeikoBarrett, KirstenEddy, JamesMilner, SamSuarez, Juan C.http://hdl.handle.net/2381/395812017-03-28T02:22:06Z2017-03-27T13:53:24ZTitle: Individual Tree Crown Delineation from Airborne Laser Scanning for Diseased Larch Forest Stands
Authors: Barnes, Chloe; Balzter, Heiko; Barrett, Kirsten; Eddy, James; Milner, Sam; Suarez, Juan C.
Abstract: Airborne laser scanning (ALS) can be utilised to derive canopy height models (CHMs) for individual tree crown (ITC) delineation. In the case of forest areas subject to defoliation and dieback as a result of disease, increased irregularities across the canopy can add complications to the segmentation of ITCs. Research has yet to address this issue in order to suggest appropriate techniques to apply under conditions of forest stands that are infected by phytopathogens. This study aimed to find the best method of ITC delineation for larch canopies affected by defoliation as a result of a Phytophthora ramorum infection. Sample plots from two study sites in Wales, United Kingdom, were selected for ITC segmentation assessment across a range of infection levels and stand characteristics. The performance of two segmentation algorithms (marker-controlled watershed and region growing) were tested for a series of CHMs generated by a standard normalised digital surface model and a pit-free algorithm, across a range of spatial resolutions (0.15 m, 0.25 m and 0.5 m). The results show that the application of a pit-free CHM generation method produced improved segmentation accuracies in moderately and heavily infected larch forest, compared to the standard CHM. The success of ITC delineations was also influenced by CHM resolution. Across all plots the CHMs with a 0.25 m pixel size performed consistently well. However, lower and higher CHM resolutions also provided improved delineation accuracies in plots dominated by larger and smaller canopies respectively. The selected segmentation method also influenced the success of ITC delineations, with the marker-controlled watershed algorithm generating significantly more accurate results than the region growing algorithm (p < 0.10). The results demonstrate that ITCs in forest stands infected with Phytophthora ramorum can be successfully delineated from ALS when a pit-free algorithm is applied to CHM generation.2017-03-27T13:53:24ZField spectroscopy and radiative transfer modelling to assess impacts of petroleum pollution on biophysical and biochemical parameters of the Amazon rainforestArellano, PaulTansey, KevinBalzter, HeikoBoyd, Doreen S.http://hdl.handle.net/2381/395472017-03-23T03:04:00Z2017-03-22T14:35:59ZTitle: Field spectroscopy and radiative transfer modelling to assess impacts of petroleum pollution on biophysical and biochemical parameters of the Amazon rainforest
Authors: Arellano, Paul; Tansey, Kevin; Balzter, Heiko; Boyd, Doreen S.
Abstract: Biophysical and biochemical plant foliage parameters play a key role in assessing vegetation health. Those plant parameters determine the spectral reflectance and transmittance properties of vegetation; therefore, hyperspectral remote sensing, particularly imaging spectroscopy, can provide estimates of leaf and canopy chemical properties. Based on the relationship between spectral response and biochemical/biophysical properties of the leaves and canopies, the PROSPECT radiative transfer model simulates the interaction of light with leaves. In this study, more than 1100 leaf samples from the Amazon forest of Ecuador were collected at several study sites, some of which are affected by petroleum pollution, and across the vertical profile of the forest. For every sample, field spectroscopy at leaf level was conducted with a spectroradiometer. The goal of this study was to assess leaf optical properties of polluted and unpolluted rainforest canopies across the vertical profile and identify vegetation stress expressed in changes of biophysical and biochemical properties of vegetation. An ANOVA followed by Holme’s multiple comparisons of means and a principal component analysis showed that photosynthetic pigments, chlorophyll and carotenoids have significantly lower levels across the vertical profile of the forest, particularly in sites affected by petroleum pollution. On the other hand, foliar water content showed significantly higher levels in the polluted site. Those findings are symptoms of vegetation stress caused by reduced photosynthetic activity and consequently decreased transpiration and water-use efficiency of the plants. Cross-comparison between SPAD-502 chlorophyll content meter index and chlorophyll content showed strong positive correlation coefficients (r = 0.71 and r2 = 0.51) which suggests that using the SPAD-502 chlorophyll index itself is sensitive enough to detect vegetation stress in a multispecies tropical forest. Therefore, the SPAD-502 can be used to assess chlorophyll content of vegetation across polluted and non-polluted sites at different canopy layers. The results presented in this paper contribute to the very limited literature on field spectroscopy and radiative transfer models applied to the vertical profile of the Amazon forest.
Description: The online version of this article (doi:10.1007/s12665-017-6536-6) contains supplementary material, which is available to authorized users.2017-03-22T14:35:59ZHigh permeability explains the vulnerability of the carbon store in drained tropical peatlandsBaird, Andy J.Low, RobertYoung, DylanSwindles, Graeme T.Lopez, Omar R.Page, Susan E.http://hdl.handle.net/2381/395322017-03-22T03:22:11Z2017-03-21T11:08:42ZTitle: High permeability explains the vulnerability of the carbon store in drained tropical peatlands
Authors: Baird, Andy J.; Low, Robert; Young, Dylan; Swindles, Graeme T.; Lopez, Omar R.; Page, Susan E.
Abstract: Tropical peatlands are an important global carbon (C) store but are threatened by drainage for palm oil and wood pulp production. The store's stability depends on the dynamics of the peatland water table, which in turn depend on peat permeability. We found that an example of the most abundant type of tropical peatland-ombrotrophic domes-has an unexpectedly high permeability similar to that of gravel. Using computer simulations of a natural peat dome (NPD) and a ditch-drained peat dome (DPD) we explored how such high permeability affects water tables and peat decay. High permeability has little effect on NPD water tables because of low hydraulic gradients from the center to the margin of the peatland. In contrast, DPD water tables are consistently deep, leaving the upper meter of peat exposed to rapid decay. Our results reveal why ditch drainage precipitates a rapid destabilization of the tropical peatland C store.2017-03-21T11:08:42ZQuantifying biomass consumption and carbon release by the California Rim Fire by integrating airborne LiDAR and Landsat-OLI dataGarcia, MarianoSaatchi, SassanKoltunov, AngelesKoltunov, AlexanderUstin, SusanRamirez, CarlosGarcia-Gutierrez, JorgeBalzter, Heikohttp://hdl.handle.net/2381/394982017-03-18T03:57:20Z2017-03-17T14:45:32ZTitle: Quantifying biomass consumption and carbon release by the California Rim Fire by integrating airborne LiDAR and Landsat-OLI data
Authors: Garcia, Mariano; Saatchi, Sassan; Koltunov, Angeles; Koltunov, Alexander; Ustin, Susan; Ramirez, Carlos; Garcia-Gutierrez, Jorge; Balzter, Heiko
Abstract: Quantifying biomass consumption and carbon release is critical to understanding the role of fires in the carbon cycle and air quality. We present a methodology to estimate the biomass consumed and the carbon released by the California Rim fire by integrating postfire airborne LiDAR and multitemporal Landsat Operational Land Imager (OLI) imagery. First, a support vector regression (SVR) model was trained to estimate the aboveground biomass (AGB) from LiDAR-derived metrics over the unburned area. The selected model estimated AGB with an R2 of 0.82 and RMSE of 59.98 Mg/ha. Second, LiDAR-based biomass estimates were extrapolated to the entire area before and after the fire, using Landsat OLI reflectance bands, Normalized Difference Infrared Index, and the elevation derived from LiDAR data. The extrapolation was performed using SVR models that resulted in R2 of 0.73 and 0.79 and RMSE of 87.18 (Mg/ha) and 75.43 (Mg/ha) for the postfire and prefire images, respectively. After removing bias from the AGB extrapolations using a linear relationship between estimated and observed values, we estimated the biomass consumption from postfire LiDAR and prefire Landsat maps to be 6.58 ± 0.03 Tg (1012 g), which translate into 12.06 ± 0.06 Tg CO2e released to the atmosphere, equivalent to the annual emissions of 2.57 million cars.2017-03-17T14:45:32ZApplying a normalized ratio scale technique to assess influences of urban expansion on land surface temperature of the semi-arid city of ErbilRasul, AzadBalzter, HeikoSmith, Clairehttp://hdl.handle.net/2381/394972017-04-19T11:12:07Z2017-03-17T14:34:07ZTitle: Applying a normalized ratio scale technique to assess influences of urban expansion on land surface temperature of the semi-arid city of Erbil
Authors: Rasul, Azad; Balzter, Heiko; Smith, Claire
Abstract: The difference between surface and air temperature within a city and its
surrounding area is a result of variations in surface cover, thermal capacity and 3-dimensional
geometry. This research has examined and quantified the decreasing daytime land surface
temperature (LST) in Erbil, Kurdistan region of Iraq, and the influence of rapid urban
expansion on urban heat/cool island effect over a 20 year period. Land Use/Land Cover
(LULC) change across this time period is also established using pixel samples. The current
study proposes the application of the Normalized Ratio Scale (NRS) to adjust the temperature
of images acquired at different date to the same range. Eleven satellite images acquired by
Landsat 4, 5, 7 and 8 during the period 1992 to 2013 are used to retrieve LST. The results
indicate that 55.3 km2 21 of city land cover changed from bare soil to urban, consequently the
mean LST of the new urbanized area decreased by 2.28°C. The NDVI of Sami Abdul-Rahman
(S.A.) Park increased from 0.09 ± 0.01 to 0.32 ± 0.11, resulting in a decrease of the mean LST
by 7.29°C. This study shows that the NRS method is appropriate for detecting temperature
trends from urbanization using remote sensing data. It also highlights that urban expansion
may lead to a decrease in daytime LST in drylands.
Description: The file associated with this record is under embargo until 12 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.2017-03-17T14:34:07ZBuoyancy mechanisms limit preservation of coleoid cephalopod soft tissues in Mesozoic LagerstättenClements, ThomasColleary, CaitlinDe Baets, KennethVinther, Jakobhttp://hdl.handle.net/2381/394372017-03-11T04:12:47Z2017-03-10T14:36:39ZTitle: Buoyancy mechanisms limit preservation of coleoid cephalopod soft tissues in Mesozoic Lagerstätten
Authors: Clements, Thomas; Colleary, Caitlin; De Baets, Kenneth; Vinther, Jakob
Abstract: Coleoid cephalopods are characterized by internalization of their shell, and are divided into the ten-armed Decabrachia (squids and cuttlefish) and the eight-armed Vampyropoda (octopuses and vampire squid). They have a rich fossil record predominantly of the limited biomineralized skeletal elements they possess: arm hooks, statoliths, mouthparts (the buccal mass) and internal shell (gladius or pen), although exquisitely preserved soft tissue coleoids are known from several Lagerstätten worldwide. Recent studies have shown that although morphological similarities between extant decabrachian gladii and fossil examples exist, no known examples of fossil decabrachians are currently known. However, molecular clock data and phylogenetic bracketing suggest that they should be present in Lagerstätten that are rich in vampyropod soft tissue fossils (i.e. Hâkel and Hâdjoula Lagerstätten, Cretaceous, Lebanon). We propose that a hitherto unknown taphonomic bias pertaining to the differing methods of buoyancy control within coleoid groups limits preservation potential. Both negatively and neutrally buoyant decabrachians use chemical buoyancy control (ammonia) whereas vampyropods do not. In the event of rapid burial in an environment conducive to exceptional preservation, ammonia dramatically decreases the ability of the decabrachian carcass to generate the required pH for authigenic calcium phosphate replacement, limiting its preservation potential. Moreover, the greater surface area and comparatively fragile dermis further decrease the potential for fossilization. This taphonomic bias may have contributed to the lack of preserved labile soft-tissues in other cephalopods groups such as the ammonoids.2017-03-10T14:36:39ZCold storage as a method for the long-term preservation of tropical dissolved organic carbon (DOC)Cook, S.Peacock, M.Evans, C. D.Page, Susan ElizabethWhelan, M.Gauci, V.Khoon, K. L.http://hdl.handle.net/2381/394232017-03-09T03:21:15Z2017-03-08T16:23:05ZTitle: Cold storage as a method for the long-term preservation of tropical dissolved organic carbon (DOC)
Authors: Cook, S.; Peacock, M.; Evans, C. D.; Page, Susan Elizabeth; Whelan, M.; Gauci, V.; Khoon, K. L.
Abstract: Fluvial fluxes of dissolved organic carbon (DOC) may represent an important loss for terrestrial carbon stores in the tropics. However, there is currently limited guidance on the preservation of tropical water samples for DOC analysis. Commonly employed preservation techniques such as freezing or acidification can limit degradation but may also alter sample properties, complicating DOC analysis. We examined the effects of cold storage at 4 °C on DOC concentration and quality in water samples collected from a tropical peat catchment. Samples were stored in the dark at 4 °C for periods of 6–12 weeks. Freeze/thaw experiments were also made. Mean DOC concentrations in samples stored for six weeks at 4 °C were 6.1 % greater than in samples stored at ambient room temperature (33 °C) over the same period. Changes in DOC concentrations, in two sample sets, during cold storage were 2.25 ± 2.9 mg L-1 (8 %) to 2.69 ± 1.4 mg L-1 (11 %) over a 12-week period. Freeze/thaw resulted in alterations in the optical properties of samples, and this in turn altered the calculated DOC concentrations by an average of 10.9 %. We conclude that cold storage at 4 °C is an acceptable preservation method for tropical DOC water samples, for moderate time periods, and is preferable to freezing or storage at ambient temperatures.2017-03-08T16:23:05ZPalaeoenvironments during a terminal Oligocene or early Miocene transgression in a fluvial system at the southwestern tip of AfricaRoberts, D. L.Neumann, F. H.Cawthra, H. C.Carr, A. S.Scott, L.Durugbo, E. U.Humphries, M. S.Cowling, R. M.Bamford, M. K.Musekiwa, C.MacHutchon, M.http://hdl.handle.net/2381/394172018-01-30T02:45:07Z2017-03-08T11:47:04ZTitle: Palaeoenvironments during a terminal Oligocene or early Miocene transgression in a fluvial system at the southwestern tip of Africa
Authors: Roberts, D. L.; Neumann, F. H.; Cawthra, H. C.; Carr, A. S.; Scott, L.; Durugbo, E. U.; Humphries, M. S.; Cowling, R. M.; Bamford, M. K.; Musekiwa, C.; MacHutchon, M.
Abstract: A multi-proxy study of an offshore core in Saldanha Bay (South Africa) provides new insights into fluvial deposition, ecosystems, phytogeography and sea-level history during the late Paleogene-early Neogene. Offshore seismic data reveal bedrock topography, and provide evidence of relative sea levels as low as − 100 m during the Oligocene. 3D landscape reconstruction reveals hills, plains and an anastomosing river system. A Chattian or early Miocene age for the sediments is inferred from dinoflagellate taxa Distatodinium craterum, Chiropteridium lobospinosum, Homotryblium plectilum and Impagidinium paradoxum. The subtropical forest revealed by palynology includes lianas and vines, evergreen trees, palms and ferns, implying higher water availability than today, probably reduced seasonal drought and stronger summer rainfall. From topography, sedimentology and palynology we reconstruct Podocarpaceae-dominated forests, Proto-Fynbos, and swamp/riparian forests with palms and other angiosperms. Rhizophoraceae present the first South African evidence of Palaeogene/Neogene mangroves. Subtropical woodland-thicket with Combretaceae and Brachystegia (Peregrinipollis nigericus) probably developed on coastal plains. Some of the last remaining Gondwana elements on the sub-continent, e.g., Araucariaceae, are recorded. Charred particles signal fires prior to the onset of summer dry climate at the Cape. Marine and terrestrial palynomorphs, together with organic and inorganic geochemical proxy data, suggest a gradual glacio-eustatic transgression. The data shed light on Southern Hemisphere biogeography and regional climatic conditions at the Palaeogene-Neogene transition. The proliferation of the vegetation is partly ascribed to changes in South Atlantic oceanographic circulation, linked to the closure of the Central American Seaway and the onset of the Benguela Current ~ 14 Ma.
Description: The file associated with this record is under embargo until 12 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.2017-03-08T11:47:04ZAge, extent and carbon storage of the central Congo Basin peatland complexDargie, Greta C.Lewis, Simon L.Lawson, Ian T.Mitchard, Edward T. A.Page, Susan E.Bocko, Yannick E.Ifo, Suspense A.http://hdl.handle.net/2381/393632017-07-11T01:45:07Z2017-02-22T14:45:58ZTitle: Age, extent and carbon storage of the central Congo Basin peatland complex
Authors: Dargie, Greta C.; Lewis, Simon L.; Lawson, Ian T.; Mitchard, Edward T. A.; Page, Susan E.; Bocko, Yannick E.; Ifo, Suspense A.
Abstract: Peatlands are carbon-rich ecosystems that cover just three per cent of Earth’s land surface1, but store one-third of soil carbon2. Peat soils are formed by the build-up of partially decomposed organic matter under waterlogged anoxic conditions. Most peat is found in cool climatic regions where unimpeded decomposition is slower, but deposits are also found under some tropical swamp forests2, 3. Here we present field measurements from one of the world’s most extensive regions of swamp forest, the Cuvette Centrale depression in the central Congo Basin4. We find extensive peat deposits beneath the swamp forest vegetation (peat defined as material with an organic matter content of at least 65 per cent to a depth of at least 0.3 metres). Radiocarbon dates indicate that peat began accumulating from about 10,600 years ago, coincident with the onset of more humid conditions in central Africa at the beginning of the Holocene5. The peatlands occupy large interfluvial basins, and seem to be largely rain-fed and ombrotrophic-like (of low nutrient status) systems. Although the peat layer is relatively shallow (with a maximum depth of 5.9 metres and a median depth of 2.0 metres), by combining in situ and remotely sensed data, we estimate the area of peat to be approximately 145,500 square kilometres (95 per cent confidence interval of 131,900–156,400 square kilometres), making the Cuvette Centrale the most extensive peatland complex in the tropics. This area is more than five times the maximum possible area reported for the Congo Basin in a recent synthesis of pantropical peat extent2. We estimate that the peatlands store approximately 30.6 petagrams (30.6 × 1015 grams) of carbon belowground (95 per cent confidence interval of 6.3–46.8 petagrams of carbon)—a quantity that is similar to the above-ground carbon stocks of the tropical forests of the entire Congo Basin6. Our result for the Cuvette Centrale increases the best estimate of global tropical peatland carbon stocks by 36 per cent, to 104.7 petagrams of carbon (minimum estimate of 69.6 petagrams of carbon; maximum estimate of 129.8 petagrams of carbon2). This stored carbon is vulnerable to land-use change and any future reduction in precipitation 7, 8.
Description: The file associated with this record is under embargo until 6 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.2017-02-22T14:45:58ZImpact of data model and point density on aboveground forest biomass estimation from airborne LiDARGarcia, MarianoSaatchi, S.Ferraz, A.Silva, C. A.Ustin, S.Koltunov, A.Balzter, Heikohttp://hdl.handle.net/2381/393552017-02-22T03:21:50Z2017-02-21T14:48:18ZTitle: Impact of data model and point density on aboveground forest biomass estimation from airborne LiDAR
Authors: Garcia, Mariano; Saatchi, S.; Ferraz, A.; Silva, C. A.; Ustin, S.; Koltunov, A.; Balzter, Heiko
Abstract: Background
Accurate estimation of aboveground forest biomass (AGB) and its dynamics is of paramount importance in understanding the role of forest in the carbon cycle and the effective implementation of climate change mitigation policies. LiDAR is currently the most accurate technology for AGB estimation. LiDAR metrics can be derived from the 3D point cloud (echo-based) or from the canopy height model (CHM). Different sensors and survey configurations can affect the metrics derived from the LiDAR data. We evaluate the ability of the metrics derived from the echo-based and CHM data models to estimate AGB in three different biomes, as well as the impact of point density on the metrics derived from them.
Results
Our results show that differences among metrics derived at different point densities were significantly different from zero, with a larger impact on CHM-based than echo-based metrics, particularly when the point density was reduced to 1 point m−2. Both data models-echo-based and CHM-performed similarly well in estimating AGB at the three study sites. For the temperate forest in the Sierra Nevada Mountains, California, USA, R2 ranged from 0.79 to 0.8 and RMSE (relRMSE) from 69.69 (35.59%) to 70.71 (36.12%) Mg ha−1 for the echo-based model and from 0.76 to 0.78 and 73.84 (37.72%) to 128.20 (65.49%) Mg ha−1 for the CHM-based model. For the moist tropical forest on Barro Colorado Island, Panama, the models gave R2 ranging between 0.70 and 0.71 and RMSE between 30.08 (12.36%) and 30.32 (12.46) Mg ha−1 [between 0.69–0.70 and 30.42 (12.50%) and 61.30 (25.19%) Mg ha−1] for the echo-based [CHM-based] models. Finally, for the Atlantic forest in the Sierra do Mar, Brazil, R2 was between 0.58–0.69 and RMSE between 37.73 (8.67%) and 39.77 (9.14%) Mg ha−1 for the echo-based model, whereas for the CHM R2 was between 0.37–0.45 and RMSE between 45.43 (10.44%) and 67.23 (15.45%) Mg ha−1.
Conclusions
Metrics derived from the CHM show a higher dependence on point density than metrics derived from the echo-based data model. Despite the median of the differences between metrics derived at different point densities differing significantly from zero, the mean change was close to zero and smaller than the standard deviation except for very low point densities (1 point m−2). The application of calibrated models to estimate AGB on metrics derived from thinned datasets resulted in less than 5% error when metrics were derived from the echo-based model. For CHM-based metrics, the same level of error was obtained for point densities higher than 5 points m−2. The fact that reducing point density does not introduce significant errors in AGB estimates is important for biomass monitoring and for an effective implementation of climate change mitigation policies such as REDD + due to its implications for the costs of data acquisition. Both data models showed similar capability to estimate AGB when point density was greater than or equal to 5 point m−2.
Description: The datasets supporting the conclusions of this article are available from the
authors upon request.2017-02-21T14:48:18Z